1. Field of the Invention
This invention relates to technologies of printers and, more specifically, to a technology for managing a plurality of jobs thrown from the host machine. A first invention relates to a network-compatible printer connected to a network system such as a LAN, while a second invention to a printer connected to a RAW-mode physical channel, such as a serial interface, a parallel interface and a USB (Universal Serial Bus) interface.
2. Description of the Related Art
The printer has various interfaces for connection to a host machine. There is known as a representative interface a network interface connected to a LAN architected by the Ethernet, or an exclusive interface, such as a serial interface, parallel interface and USB interface. The exclusive interface is distinguished as a physical channel in a RAW mode because of not making data conversion by a protocol stack, such as of the network interface.
The printer having exclusive interface connection receives print data from the host machine while controlling data flow by BUSY and READY signals in accordance with the process capability (i.e. printing speed) such as a use status of the receiving buffer. The printing data is typically supplied in the form of print job data generated by the printer driver on the host machine to the printer. The printer sequentially interprets the print job data stored in the receiving buffer to generate image data for print output, and loads this in the image memory and thereafter supplies to the print engine. This allows the printer to realize print onto a print recording medium, such as a hard paper.
In such exclusive interface connection, the host machine as a transmission source is definite and the control of data flow is at the initiative of the printer. Consequently, the printer merely processes print job data in the reception sequence thereof. That is, even where print job data is next thrown before the completion of the print process on the basis of the print job data first thrown from the host machine, the printer if sequentially processing a series of data can execute the print process without interference without the need to explicitly distinguish the print job data therein.
Meanwhile, the network-compatible printer through a network interface generally has a print server at an inside or outside of the printer. This print server has a print-spooler function to perform network communication with the host machine and accepting print job data once stored in a hard disk unit or the like and thereafter sequentially taken out thereof and forwarded for the print process.
In the meanwhile, there are cases that the user provides a print instruction from the host machine to throw print job data into the printer and thereafter intends to cancel the print process based upon the print job data. Immediately after forwarding the print job data by the host machine, the user can cancel the print job data stored in the hard disk or the like by deleting the print job data stored on the hard disk unit or the like. Meanwhile, after the printer has forwarded the print job data to a print process, the user must forcibly reset the memory content within the printer main body by use of a reset button provided on the printer or power off the printer itself.
Accordingly, there has been inconvenience that, where canceling print after throwing a plurality of print job data into the printer, all the print job data thrown be cleared out of the memory. In other words, it is impossible for such a printer to execute cancellation of particular print job data only.